This invention relates to compounds useful for antiviral applications. More particularly, this invention relates to non-nucleoside HIV-1 reverse transcriptase inhibitors having a common alkenyldiarylmethane structure.
The non-nucleoside HIV-1 reverse transcriptase inhibitors (NNRTIs) are a structurally diverse set of compounds that inhibit reverse transcriptase by an allosteric mechanism involving binding to a site adjacent to the deoxyribonucleoside triphosphate binding site of the enzyme. Familiar examples of NNRTIs include hydroxyethoxymethylphenylthiothymine (HEPT), tetrahydroimidazobenzodiazepinone (TIBO), dipyridodiazepinone (nevirapine), pyridinone, bis(heteroaryl)piperazine (BHAP), tertbutyldimethylsilylspiroaminooxathiole dioxide (TSAO), and xcex1-anilinophenylacetamide (xcex1-APA) derivatives. Nevirapine has recently been approved for clinical use as an anti-AIDS agent.
The use of NNRTIs as anti-AIDs agents has been limited by the development of viral resistance to the NNRTIs. Although the rapid emergence of resistant viral strains has hampered the clinical development of the NNRTIs for the treatment of AIDS, several strategies have emerged for overcoming resistance, including switching to another NNRTI to which the virus has remained sensitive, using higher doses of the NNRTI against the resistant strain, employing of combinations of agents which elicit mutations that counteract one another, and combining NNRTIs with nucleoside reverse transcriptase inhibitors (RTIs). Accordingly, a need remains for additional NNRTIs having unique patterns of resistance mutations in order to facilitate the application of these strategies.
The synthesis and biological evaluation of NNRTIs in the alkenyldiarylmethane (ADAM) series has recently been reported. Several of the alkenyldiarylmethane compounds were disclosed as inhibiting the cytopathic effect of a wide variety of HIV-1 strains in CEM, MT-4, and monocyte-macrophage cultures. (Cushman et al. J. Med. Chem 1996, 39, 3217-3227) The most potent of these disclosed compounds was ADAM I (1), which displayed anti-HIV activity vs. a wide range of HIV-1 isolates and was synergistic with AZT. However, the potency of ADAM I (1) against a variety of non-resistant HIV-1 strains was lower than that generally observed with many of the known NNRTIs, ranging from 0.56 xcexcM vs. HIV-165 in MT-4 cells to 151 xcexcM vs. HIV-1N119 in MT-4 cells.
The present invention is directed to a series of ADAM I related compounds that are inhibitors of reverse transcriptase activity and inhibit the cytopathic activity of HIV strains.
The design of additional alkenyldiarylmethanes has been aided by the availability of X-ray structures of HIV-1 reverse transcriptase complexed with nevirapine, xcex1-APA, and TIBO. These structures reveal that nevirapine, xcex1-APA, and TIBO assume a similar butterfly shape and bind to the enzyme in a similar manner with considerable overlap. Analysis of the X-ray crystallography structures allows the construction of a hypothetical model of the binding of ADAM I (1) to HIV-1 RT. The model was constructed by overlapping the structure of ADAM I (1) with that of nevirapine (2) in the binding pocket of HIV-1 RT (Sculpt(copyright) 2.0, Interactive Simulations, San Diego, Calif.). During this process, it was assumed that the hexenyl side chain of ADAM I (1) would point in the same direction as the cyclopropyl substituent of nevirapine. The nevirapine structure was then removed, the structure of the protein xe2x80x9cfrozenxe2x80x9d, and the energy of the complex minimized while allowing the ligand to move. The resulting hypothetical structure was consistent with the reported structures of NNRTI enzyme complexes, and was also supported by prior mutagenesis studies of the alkenyldiarylmethane binding site of HIV-1 reverse transcriptase, in which it was determined that the resistance mutations to ADAM 1 circumscribe a well-defined binding pocket.
According to the model generated by this analysis, the end of the ADAM I (1) side chain occupies a cavity formed by Glu 138, Lys 103, Tyr 181, and Val 179 of the HIV-1 RT. Several functional groups are present that would be capable of hydrogen bonding, including the phenolic hydroxyl group of Tyr 181, the backbone amide and side chain carboxylate of Glu 138, and the terminal amino group of Lys 103. It was anticipated that the incorporation of functional groups at the end of the alkenyl chain of the ligand which are capable of hydrogen bonding might allow favorable interactions with the adjacent residues of the RT. Therefore, alkenyldiarylmethane related compounds were synthesized to incorporate functionalities at the end of the alkenyl side chain that would be capable of hydrogen bonding.
The present invention is directed to non-nucleoside compounds that inhibit reverse transcriptase activity, their pharmaceutical compositions and methods utilizing such compounds/compositions for treating patients suffering from a viral infection. More particularly the compounds of the present invention are useful for treating patients suffering from a disease of retroviral origin, such as AIDs.
The compounds of the present invention are alkenyldiarylmethane compounds of formula I: 
wherein X is selected from the group consisting of 
wherein R1 and R6 are H or halo;
R2 and R5 are independently OR11;
R3 and R4 are CO2R12 or Z; or
R2 and R3 taken together with the carbon atoms (C2, C3) to which they are attached and R4 and R5 taken together with the carbon atoms (C4, C5) to which they are attached form a 5- or 6-membered ring of the formula 
xe2x80x83wherein Q is O, S, or Se;
R1 is C1-C4 alkyl,
B is xe2x80x94OR1 or xe2x95x90O, and
r is 1 or 0;
provided that when B is xe2x95x90O, r is 1 and bond a is a single bond and when B is xe2x80x94OR1, r is 0 and bond a is a double bond;
R7 is hydrogen;
R8 is selected from the group consisting of (CH2)mOR13, (CH2)mN3, (CH2)mCOOR14, (CH2)mZ, and (CH2)mNH2;
R9 and R10 are independently selected from the group consisting of H, (C1-C5) alkyl, (CH2)nOR13, (CH2)nN3, (CH2)nCOOR14, (CH2)mZ and (CH2)nNH2;
R11, R12, R13 and R14 are independently selected from the group consisting of H and (C1-C5) alkyl; m is 1-4; n is 0-4: and Z is selected from the following subtituent groups: 
xe2x80x83with the proviso that when X is 
R8 is not (CH2)2OH.
In one embodiment of this invention there is provided a compound of the above formula I, wherein X is 
R1 and R6 are independently Br or Cl, R2 and R5 are each OCH3, R3 and R4 are each CO2CH3 or Z, R7 is H and R8 is (CH2)mOH, (CH2)mCOOCH3, (CH2)mZ, or (CH2)mN3, wherein m is 2 or 3. These compounds inhibit the cytopathic effect of HIV-1RF in CEM-SS cells. (See Table 1 below).
In another embodiment of this invention there is provided a reverse transcriptase inhibiting compound of the above formula I wherein X is 
R1 and R6 are halo;
R2 and R5 are OCH3;
R3 and R4 are CO2CH3;
R7 is H;
R8 is (C2-C5) alkyl, (CH2)mOR13, (CH2)mN3, (CH2)mCOOR14, (CH2)mZ, and (CH2)mNH3;
R13 and R14 are independently selected from the group consisting of H and (C1-C5) alkyl; and m is 2-4.
In still another embodiment of the invention R1 and R6 are both chloro or bromo.
The compounds of this invention are readily formulated into pharmaceutical compositions, also within the scope of this invention, for use in the presently described method for treatment of patients suffering from a disease of retroviral origin. In one embodiment of this invention, the pharmaceutical composition comprises a reverse transcriptase inhibitory effective amount of a compound of formula I: 
wherein X is selected from the group consisting of 
wherein R1 and R6 are H or halo;
R2 and R5 are independently OR11;
R3 and R4 are CO2R12 or Z; or
R2 and R3 taken together with the carbon atoms (C2, C3) to which they are attached and R4 and R5 taken together with the carbon atoms (C4, C5) to which they are attached form a 5- or 6-membered ring of the formula 
xe2x80x83wherein Q is O, S, or Se;
R1 is C1-C4 alkyl,
B is xe2x80x94OR1 or xe2x95x90O, and
r is 1 or 0;
provided that when B is xe2x95x90O, r is 1, and bond a is a single bond, and when B is xe2x80x94OR1, r is 0 and bond a is a double bond;
R7 is hydrogen;
R8 is selected from the group consisting of (CH2)mOR13, (CH2)mN3, (CH2)mCOOR14, (CH2)mZ, and (CH2)mNH2;
R9 and R10 are independently selected from the group consisting of H, (C1-C5) alkyl, (CH2)nOR13, (CH2)nN3, (CH2)nCOOR14, (CH2)mZ and (CH2)nNH2;
R11, R12, R13 and R14 are independently selected from the group consisting of H and (C1-C5) alkyl; m is 1-4; n is 0-4 and Z is as defined above; and
a pharmaceutically acceptable carrier.
Another pharmaceutical composition within the scope of this invention comprises a reverse transcriptase inhibiting compound of the above formula I wherein X is 
R1 and R6 are halo;
R2 and R5 are OCH3,
R3 and R4 are CO2CH3 or Z;
R8 is (C2-C4) alkyl, (CH2)mOR13, (CH2)mN3, (CH2)mCOOR14, (CH2)mZ and (CH2)mNH3;
R13 and R14 are independently selected from the group consisting of H and (C1-C5) alkyl; and m is 2 or 3, and a pharmaceutically acceptable carrier.
The present invention further provides pharmaceutical formulations comprising an effective amount of an alkenyldiarylmethane compound for use in the present method for treating a patient suffering from a disease of retroviral origin. As used herein, an effective amount of the alkenyldiarylmethane compound is defined as the amount of the compound which, upon administration to a patient, alleviates or eliminates symptoms of the disease, or reduces or eliminates detectable levels of the virus in the treated patient.
The effective amount to be administered to a patient is typically based on body surface area, patient weight, patient condition, and the potency, efficacy and therapeutic index of the compound being administered. Body surface area may be approximately determined from patient height and weight (see e.g., Scientific Tables, Geigy Pharmaceuticals, Ardley, N.Y., pages 537-538 (1970)). Effective doses will vary, as recognized by those skilled in the art, dependent on route of administration, excipient usage and the possibility of co-usage with other therapeutic treatments including other anti-viral agents.
The pharmaceutical formulation may be administered via the parenteral route, including subcutaneously, intraperitoneally, intramuscularly and intravenously. Examples of parenteral dosage forms include aqueous solutions of the active agent, in a isotonic saline, 5% glucose or other well-known pharmaceutically acceptable liquid carrier. In one aspect of the present embodiment, the alkenyldiarylmethane compound is dissolved in a saline solution containing 5% of dimethyl sulfoxide and 10% Cremphor EL (Sigma Chemical Company). Additional solubilizing agents well-known to those familiar with the art can be utilized as pharmaceutical excipients for delivery of the present compounds.
The present compounds can also be formulated into dosage forms for other routes of administration utilizing well-known methods. The pharmaceutical compositions can be formulated, for example, in dosage forms for oral administration in a capsule, a gel seal or a tablet. Capsules may comprise any well-known pharmaceutically acceptable material such as gelatin or cellulose derivatives. Tablets may be formulated in accordance with conventional procedure by compressing mixtures of the active compound and solid carriers, and lubricants well-known to those familiar with the art. Examples of solid carriers include starch, sugar, bentonite. The compounds of the present invention can also be administered in a form of a hard shell tablet or capsule containing, for example, lactose or mannitol as a binder and conventional fillers and tableting agents.
Typically, oral dosage levels range from 50-500 mg per dose, administered from 1 to 4 times per day. More typically, oral dosage levels ranging from 100 to 250 mg/dose are administered 1 to 4 times per day. With respect to parenteral dosing, levels between 25 and 250 mg are typically administered 1 to 4 times per day. Dosing regimens with lower or higher amounts of drug may be indicated depending upon the patients clinical state and the potency of the compound being administered.
The anti-viral activity of the described compounds was measured utilizing two different assays. The first assay measures the effectiveness of the alkenyldiarylmethane compound to inhibit reverse transcriptase activity, and the second assay measured the compound""s ability to inhibit the cytopathic activity of HIV-1 to cells cultured in vitro. The mechanism of action for the disclosed compounds"" antiviral activities is believed to be due at least in part to the compounds"" ability to inhibit reverse transcriptase (RT) activity. Several of the disclosed ADAM compounds have an inhibitory effect on RT and yet do not exhibit a detectable inhibitory effect on viral cytopathicity in the HIV cell assay. This may be the result of the failure of the compound to penetrate the cell membrane. For example, compound 21 has activity as an RT inhibitor and yet no detectable inhibitory cytopathic effect was detected. The inactivity of 21 might possibly be due to the fact that the amino group is protonated at the pH of the assay medium and therefore should be less able to penetrate cellular membranes. Such compounds may have utility as antiviral agents, if they can be formulated as prodrugs, using techniques known to those skilled in the art, or through the use of other techniques that are known to increase cellular uptake of compounds.